Spurious Hyperphosphatemia in Patients on Hemodialysis With Catheters Brigitte Schiller, MD, Bhupinder Virk, MD, Martin Blair, MS, Amy Wong, MT, John Moran, MB, BS  American Journal of Kidney Diseases  Volume 52, Issue 3, Pages 617-620 (September 2008) DOI: 10.1053/j.ajkd.2008.03.033 Copyright © 2008 National Kidney Foundation, Inc. Terms and Conditions

Figure 1 Routine phosphate results from patient 1 during 12 months. To convert plasma phosphate in mg/dL to mmol/L, divide by 0.3229. American Journal of Kidney Diseases 2008 52, 617-620DOI: (10.1053/j.ajkd.2008.03.033) Copyright © 2008 National Kidney Foundation, Inc. Terms and Conditions

Figure 2 Phosphate levels in blood from a healthy volunteer measured in a 4.5-mL blood volume. Baseline plus the result after the addition of 35, 70, and 105 μL of alteplase show a linear increase in phosphate concentrations. To convert phosphate in mg/dL to mmol/L, divide by 0.3229. American Journal of Kidney Diseases 2008 52, 617-620DOI: (10.1053/j.ajkd.2008.03.033) Copyright © 2008 National Kidney Foundation, Inc. Terms and Conditions

Figure 3 Whiskers plot of phosphate levels from patient 2 during 1 year on days that alteplase had been instilled into the catheter and on days without alteplase. The mean and range of the values are higher on days after alteplase compared with draws on days without alteplase. The single outlying value of 11.8 mg/dL (closed square) was obtained after the patient skipped 2 consecutive hemodialysis sessions during vacation. To convert phosphate in mg/dL to mmol/L, divide by 0.3229. American Journal of Kidney Diseases 2008 52, 617-620DOI: (10.1053/j.ajkd.2008.03.033) Copyright © 2008 National Kidney Foundation, Inc. Terms and Conditions